With the IC composed by Metal Oxide Semiconductor (MOS) devices widely used in many fields, the reliability problem caused by the degradation of electrical properties in production and application process is becoming increasingly prominent. The progress and updating of microelectronics technology are marked by the reduction in feature size of IC and the increase of integration. With the rapid development of microelectronics technology, the feature size of IC decreases to nanometer, and the area percent of metal interconnects becomes larger and larger in the whole chip. The problem of EM failure in metal interconnect has become bottleneck for the development of large-scale IC, which has become the focus of the research for reliability of IC. The EM is caused by the migration of ions in metal under the action of current distribution, and is the transport of material caused by the movement of electrons acting on metal atoms in the metal interconnect, which is shown as increase in resistance value and with the increasing of the resistance to a certain extent causes metal film local loss to create an cavity or causes metal film local accumulation to create a hillock or whisker, resulting in saltation and failure that severely affect the life of the IC. The main behaviors of IC failure caused by EM are: (1) creating a cavity in metal interconnect to increase the resistance; (2) the cavity growing and passing through the interconnect wire to create an open circuit; (3) creating a whisker in metal interconnect to cause a layer short circuit; and (4) the whisker growing and passing through the passivation layer to cause a etching source.
A prognostic circuit had been designed in the prior art based on the EM failure mechanism of IC, which outputs a prognostic signal when the resistance increases to a specified threshold, so as to avoid the critical failure of the system caused by EM failure. However, in a practical application, both the increased resistance caused by EM and the short circuit caused by whiskers may occur. The above solution only indicates the increased resistance failure that is caused by EM, and not a circuit which indicates the short circuit failure that is caused by EM.